Various golf balls, golf ball layers, and methods of making golf balls are generally known in the art. The centers may be fluid-filled or solid. Such golf balls may have a multilayer construction. Golf balls may have a wound layer or may be solid.
Regardless of the form of the ball, players generally seek a golf ball that embodies a beneficial combination of properties, for example, such as maximum distance, which requires a high initial velocity upon impact. Therefore, golf ball manufacturers are continually searching for new ways in which to provide golf balls that deliver the maximum performance for golfers of varying skill levels.
Polyurethane materials are sometimes used in golf ball layers to provide a beneficial mix of properties. For example, U.S. Pat. Nos. 3,147,324; 5,816,937; and 5,885,172 are directed to golf balls, or methods for making such, having a polyurethane outer cover.
U.S. Pat. No. 4,123,061 teaches a golf ball made from a polyurethane prepolymer of polyether, and a curing agent, such as a trifunctional polyol, a tetrafunctional polyol, or a diamine.
U.S. Pat. No. 5,334,673 discloses the use of two categories of polyurethane available on the market, i.e., thermoset and thermoplastic polyurethanes, for forming golf ball covers and, in particular, thermoset polyurethane covered golf balls made from a composition of polyurethane prepolymer and a slow-reacting amine curing agent and/or a difunctional glycol.
U.S. Pat. No. 3,989,568 discloses a three-component system employing either one or two polyurethane prepolymers and one or two polyol or fast-reacting diamine curing agents. The reactants chosen for the system must have different rates of reactions within two or more competing reactions.
U.S. Pat. No. 4,123,061 discloses a golf ball made from a polyurethane prepolymer of polyether and a curing agent, such as a trifunctional polyol, a tetrafunctional polyol, or a fast-reacting diamine curing agent.
U.S. Pat. No. 5,334,673 discloses a golf ball cover made from a composition of a thermosetting polyurethane prepolymer and a slow-reacting polyamine curing agent and/or a difunctional glycol. Resultant golf balls are found to have improved shear resistance and cut resistance compared to covers made from balata or SURLYN®.
U.S. Pat. No. 5,692,974 discloses methods of using cationic ionomers in golf ball cover compositions. Additionally, the patent relates to golf balls having covers and cores incorporating urethane ionomers. Improved resiliency and initial velocity are achieved by the addition of an alkylating agent, such as t-butyl-chloride, which induces ionic interactions in the polyurethane to produce cationic type ionomers.
PCT Publication WO 98/37929 discloses a composition for golf ball covers that includes a blend of a diisocyanate/polyol prepolymer and a curing agent comprising a blend of a slow-reacting diamine and a fast-reacting diamine. Improved “feel,” playability, and durability characteristics are exhibited.
U.S. Pat. No. 5,908,358 discloses a urethane golf ball cover cured with a polyamine or glycol and an epoxy-containing curing agent. The urethane material in the golf ball cover also exhibits a tensile modulus of about 5 ksi to 100 ksi. Improved shear resistance characteristics are seen with these golf ball covers.
Interpenetrating polymer networks, or IPNs, are occasionally used to improve key physical properties or to aid in the compatibilization of the components of a polymer mixture or blend. Different kinds of IPNs and the ways in which they may be made are available from a number of sources in the literature, such as, for example, in Advances in Interpenetrating Polymer Networks, Volume 4, by Frisch & Klempner, and in Interpenetrating Polymer Networks by Klempner, Sperling, & Utracki. In addition, many patents describe compositions and methods for synthesizing various types of IPNs containing various components.
U.S. Pat. No. 5,786,426 discloses an IPN based on polyisoprene and polyurethane used for medical devices, the formation of which was accomplished by swelling a thermoplastic polyurethane with THF at an increased temperature into which cis-polyisoprene was blended and peroxide initiators were dispersed for crosslinking.
U.S. Pat. No. 5,709,948 discloses a semi-IPN prepared by reacting olefinic homopolymers with epoxy resin in the presence of an epoxy curative agent, such as a triarylsulfonium hexafluorophosphate.
U.S. Pat. No. 5,674,942 discloses a homogeneous IPN having a single glass transition temperature made by reacting a mixture of di- or poly-amines with a di- or poly-isocyanate to form a polyurea in the presence of acrylic ester monomers, to be polymerized with free radical initiators, also in the presence of tertiary amines.
U.S. Pat. No. 5,648,432 discloses a method for improving the fracture toughness, microcracking resistance, thermal and mechanical performance of high-temperature resistant polymers, such as polymers made from bismaleimides or imide-sulfones or polysulfones, polyamides, or polyimides, by dispersing them in monomers or prepolymers of low-temperature durable polymers, such as urethane-ethers, urethane-esters, ester-esters, ether-esters, ether-amides, ester-amides, silanes, siloxanes, or diene homopolymers or copolymers.
U.S. Pat. No. 5,539,053 discloses an IPN containing a glassy polymer, such as PMMA or polyacrylates, in which acrylate monomers are polymerized with radical initiators such as azobisisobutyronitrile (AIBN) in the presence of urethane prepolymers and polyol curative agents.
U.S. Pat. No. 5,331,062 discloses IPNs containing epoxy polymers with acrylate monomers or polyurethane precursors.
U.S. Pat. No. 5,306,784 discloses a tough, processable semi-IPN made by mixing monomer precursors of polyimides having an acetylene group with monomer precursors of thermoplastic polyimides. Alternately, either set of the monomer precursors may be dispersed in monomer precursors of low modulus polymers.
U.S. Pat. No. 5,241,020 discloses the preparation of a mixture including at least two different compounds that react with each other in the absence of free radical initiators and at least one monomer having a carbon-carbon double bond that polymerizes in the presence of free radical initiators. Examples of the former component include polyurethane or poly-epoxy precursors, while examples of the latter component include acrylates, methacrylates, acrylonitriles, vinyl acetates, and other vinyl monomers.
U.S. Pat. No. 5,210,109 discloses rubber-modified IPNs prepared by swelling a crosslinked polymer in monomers, oligomers, or macromonomers of vinyl acrylates or other vinyl moieties, which are then polymerized.
U.S. Pat. No. 5,084,513 discloses the dissolution of a polyalkene, such as polyethylene or polypropylene, with monomers having vinyl aromatic or acrylate-containing moieties into which a free radical initiator is added to polymerize the monomers.
U.S. Pat. No. 4,923,934 discloses the formation of an IPN from the reaction of a blocked urethane prepolymer, a polyol, and epoxy resin, and an epoxy-catalyzing agent, such as an anhydride.
Hua et. al., in J. Polym. Sci., 1999, 37, 3568, disclose an IPN based on epoxy resin and urethane acrylate formed from an epoxy-grafted polypropylene oxide and urethane acrylate precursors.
Japanese Patent Publication Nos. JP 62-014869 and JP 62-014870 disclose IPNs based on polybutadiene rubber crosslinked by vulcanization and an ionomeric phenol-formaldehyde resin network, which IPNs are used in solid golf ball centers.
U.S. Pat. Nos. 5,542,677; 5,591,803; and 6,100,336 disclose golf ball cover compositions containing blends of neutralized carboxylic acid-containing polymers with ethylene-alkyl acrylate copolymers. These patents suggest that the neutralization of the carboxylic acid-containing polymer, thus forming an ionomer, in the presence of the ethylene-alkyl acrylate copolymer may result in an IPN or alternately may cause dynamic vulcanization.
It is desirable to improve the compatibility, as well as the thermal and mechanical properties, of polymers and/or polymer blends in the core or any layer disposed therearound in golf ball applications.